package com.hg.observer;

/**
 * @Author: skh
 * @Date: 2018/10/29 10:09
 * @Description:
 */
public interface Observable {

    void addObserver(Observer observer);

    void deleteObserver(Observer observer);

    void notifyObserver();

    void notifyObserver(Object arg);

    void deleteObservers();

    void setChanged();

    void clearChanged();

    Boolean hasChanged();

    Integer countObservers();
}
